Owl post is a wizarding system of sending messages or items using owls as the carriers. Besides the Owl Post Office, individuals and organisations with their own owls use them as their mail bearers. Harry Potter's owl, Hedwig, was used as his primary means of communicating with his friends and his godfather, Sirius Black. Hogwarts School of Witchcraft and Wizardry had a number of owls that anyone at the school could use. They, along with students' personal owls, were kept in the Owlery.

Post owls are quite intelligent, and can usually find their mail's recipient with little to no direction.

Other birds can be used for delivering messages. Sirius Black, while in hiding, sent unspecified tropical birds as message carriers while communicating with Harry Potter, leading Harry to speculate that Sirius was hiding in a warmer environment than England. However, the preponderant bird used for messaging was the owl. Muggles have their own form of post and therefore do not use owls, nor were they generally aware that owls or other birds could be used for correspondence.